[docs] debug qml

docs/hacking-qml.rst

@@ -4,3 +4,9 @@ QML best practices
 * lint your qml files::
 
   make qmllint
+
+Debugging
+---------
+In windows you need to add some flags to obtain QML debug:
+
+  QT_FORCE_STDERR_LOGGING=1 QT_LOGGING_DEBUG=1 ./riseup-vpn.exe